Day 1:

McLaren Honda is off to a much better start than they were one year ago. Jenson Button managed to pilot the new MP4-31 to a best time of 1:26.735s over 84 laps. Reports are that the car sounds healthier than last year suggesting that efficiency has improved. Interestingly, a close look confirms the MP4-31 features a unique front suspension layout with the rear control arms set low on the chassis, lower than any other car on the grid. This can be presumed to better condition the airflow going to the rear of the car.
Fast lap honors go to Sebastian Vettel who turned a 1:24.939s in the Ferrari. The distance crown goes to Lewis Hamilton who ran 157 laps in the Mercedes. Also of note, the HAAS F1 car turned its first-ever laps with Romain Grosjean behind the wheel despite suffering a front wing failure early-on. At least three teams have suggested that their liveries will change by the time we get to Melbourne.

1. Vettel, Ferrari, 1m24.939s, 69 laps
2. Hamilton, Mercedes, 1m25.409s, 157 laps
3. Ricciardo, Red Bull, 1m26.044s, 87 laps
4. Bottas, Williams, 1m26.091s, 80 laps
5. Button, McLaren, 1m26.735s, 84 laps
6. Celis, Force India, 1m26.298s, 58 laps
7. Sainz, Toro Rosso, 1m27.180s, 55 laps
8. Ericsson, Sauber, 1m27.555s, 88 laps
9. Wehrlein, Manor, 1m28.282s, 54 laps
10. Grosjean, Haas, 1m28.399s, 31 laps
11. Palmer, Renault, 1m29.365s, 37 laps

Day 2:

Another smooth day of testing for McLaren Honda as the news of Yasuhisa Arai’s departure as motorsports director permeates the grid. Fernando Alonso took the wheel of the MP4-31 for the first time to execute what seems to be a very thorough aero evaluation program today.
The new Pirelli Ultra Soft made its debut on several cars today offering instant lap time improvements of over one second. It was these tires that propelled Sebastian Vettel to a fast lap time of 1:22.810s. Mercedes again logged the the most miles with Rosberg completing an impressive 172 laps.

1. Vettel, Ferrari, 1m22.810s, 136 laps
2. Ricciardo, Red Bull, 1m23.525s, 112 laps
3. Perez, Force India, 1m23.650s, 101 laps
4. Rosberg, Mercedes, 1m24.867s, 172 laps
5. Ericsson, Sauber, 1m25.237s, 108 laps
6. Gutierrez, Haas, 1m25.524s, 79 laps
7. Bottas, Williams, 1m25.648s, 134 laps
8. Wehrlein, Manor, 1m25.925s, 71 laps
9. Alonso, McLaren, 1m26.082s, 79 laps
10. Palmer, Renault, 1m26.189s, 42 laps
11. Verstappen, Toro Rosso, 1m26.539s, 121 laps

Day 3:

Not the smoothest day for McLaren Honda as a small fire caused by a hydraulic leak hampered running toward the end of the session. Button managed 51 laps with a best time of 1:26.919s. Alonso takes the wheel again tomorrow.
Mercedes quietly continues to log the miles as a split effort between Hamilton and Rosberg yielded 164 laps, the latter being the faster of the two. Fast lap honors go to Nico Hulkenberg in the Force India with a 1:23.110s. Ferrari did not fare so well with Raikkonen being stuck in the garage for much of the morning with fuel system issues. Kevin Magnussen returned to the track and had a good day with Renault logging 110 laps and going 4th fastest, however the car did stop twice for unspecified issues.

1. Hulkenberg, Force India, 1m23.110s, 99 laps
2. Grosjean, Haas, 1m25.874s, 82 laps
3. Raikkonen, Ferrari, 1m25.977s, 77 laps
4. Magnussen, Renault, 1m26.014s, 110 laps
5. Rosberg, Mercedes, 1m26.084s, 74 laps
6. Sainz, Toro Rosso, 1m26.239s, 161 laps
7. Nasr, Sauber, 1m26.392s, 115 laps
8. Hamilton, Mercedes, 1m26.421s, 87 laps
9. Kvyat, Red Bull, 1m26.497s, 74 laps
10. Massa, Williams, 1m26.712s, 109 laps
11. Button, McLaren, 1m26.919s, 71 laps
12. Haryanto, Manor, 1m28.249s, 77 laps

Day 4:

Shades of 2015 emerged on the final testing day at Barcelona as the McLaren Honda, hampered by a coolant leak, failed to set a time. McLaren has to be pleased on some level because they did cover a respectable distance over the four day test and are rumored not to have their final spec. power unit installed yet. Still, efforts over winter have clearly not solved all of their issues.
Kimi Raikkonen piloted the Ferrari to the fastest lap of the day with a 1:23.477s on the new Pirelli ultra soft tire. Distance honors go to Kevin Magnussen who drove his Renault to an impressive 153 laps despite the car stopping on track at the end of the session. Of note, Mercedes quietly tallied the miles without attempting to log a fast lap throughout the test, this is evidenced by the fact that the team did not fit the soft tire. Be assured that all teams are nervous to see what kind of time the 2016 Silver Arrow can post when driven hard and on the soft or ultra soft tire.

1. Raikkonen, Ferrari, 1m23.477s, 80 laps
2. Kvyat, Red Bull, 1m24.293s, 96 laps
3. Celis, Force India, 1m24.840s, 75 laps
4. Magnussen, Renault, 1m25.263s, 153 laps
5. Verstappen, Toro Rosso, 1m25.393s, 110 laps
6. Nasr, Sauber, 1m26.053s, 121 laps
7. Rosberg, Mercedes, 1m26.187s, 86 laps
8. Hamilton, Mercedes, 1m26.295s, 88 laps
9. Massa, Williams, 1m26.483s, 54 laps
10. Gutierrez, Haas, 1m27.802s, 89 laps
11. Haryanto, Manor, 1m28.266s, 51 laps
12. Alonso, McLaren, No time